▎ 摘　　要

The changeable structure of 2D graphene nanosheets makes the Pt-based nanoparticles (NPs) possess a low efficiency toward oxygen reduction reaction (ORR) and a short lifetime for proton exchange membrane fuel cells. Thus, a unique TiC@graphene core-shell structure material with low surface energy is designed and prepared by an in situ forming strategy, and firstly applied as a stable support of Pt NPs. The as-prepared Pt/GNS@TiC catalyst presents a high activity. Especially, its ORR stability is remarkably improved. Even after 15000 potential cycles, the half-wave potential and mass activity toward ORR have almost no change. This can be attributed to that the graphene nanosheet existing in a sphere shape effectively avoids the restacking or folding caused by the giant surface tension in 2D graphene nanosheets, impeding the decrease of the triple-phase boundary on Pt NPs. Significantly, the power density of fuel cells with our novel catalyst reaches 853 mV cm(-2) under a low Pt loading (0.25 mgPt cm(-2)) and H-2/Air conditions. These indicate the new ceramic@graphene core-shell nanocomposite is a promising application in fuel cells and other fields. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.